CVE-2014-2015 in FreeRADIUS
Summary
by MITRE
Stack-based buffer overflow in the normify function in the rlm_pap module (modules/rlm_pap/rlm_pap.c) in FreeRADIUS 2.x, possibly 2.2.3 and earlier, and 3.x, possibly 3.0.1 and earlier, might allow attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long password hash, as demonstrated by an SSHA hash.
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Analysis
by VulDB Data Team • 06/09/2021
The vulnerability identified as CVE-2014-2015 represents a critical stack-based buffer overflow flaw within the FreeRADIUS authentication server software. This issue specifically affects the normify function located in the rlm_pap module, which handles password authentication processes within the RADIUS protocol implementation. The vulnerability impacts multiple versions of FreeRADIUS including 2.x series up to 2.2.3 and 3.x series up to 3.0.1, making it a widespread concern across the software's major releases. The flaw manifests when processing password hashes, particularly SSHA (Salted Secure Hash Algorithm) hashes, which can be exploited by malicious actors to manipulate the authentication flow.
The technical mechanism behind this vulnerability involves improper input validation within the normify function where the software fails to adequately check the length of password hash data before attempting to store it in a fixed-size stack buffer. When an attacker provides an excessively long password hash, typically exceeding the allocated buffer space, the function writes beyond the intended memory boundaries, causing stack corruption. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity issue in the Common Weakness Enumeration catalog. The overflow can result in unpredictable behavior including program crashes, memory corruption, and potentially arbitrary code execution depending on the memory layout and exploitation conditions.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it creates potential entry points for more sophisticated attacks within network infrastructure. When exploited successfully, the buffer overflow could allow attackers to execute arbitrary code with the privileges of the FreeRADIUS service, potentially compromising the entire authentication infrastructure. This is particularly concerning in environments where FreeRADIUS serves as a central authentication server for network access control, wireless authentication, or VPN services. The vulnerability's exploitation requires minimal prerequisites, as attackers only need to submit a specially crafted long password hash during the authentication process, making it an attractive target for both casual attackers and organized threat groups. The attack vector aligns with ATT&CK technique T1566.002 for credential access through phishing with malicious attachments, though in this case the malicious input is embedded within the authentication process itself.
Mitigation strategies for CVE-2014-2015 should prioritize immediate software updates to versions that contain patches addressing the buffer overflow in the normify function. Organizations should implement input validation measures at network boundaries to detect and block unusually long password hash values before they reach the FreeRADIUS server. Network segmentation and access controls should be strengthened to limit potential exploitation paths, while monitoring systems should be configured to detect unusual authentication patterns that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation in authentication systems and the potential for seemingly benign authentication inputs to become attack vectors. Security teams should conduct comprehensive vulnerability assessments to identify any systems running affected FreeRADIUS versions and ensure proper patch management protocols are in place to prevent similar issues in other network services.